1. Field of the Invention
The present invention relates to system and method of measuring a self-position of a mobile robot using a camera and artificial landmarks in a home and a general office environment, and more particularly, to localization system and method of a mobile robot based on a camera and artificial landmarks, the artificial landmarks having a wireless LED flash function in an invisible wavelength band, the camera being provided with a wide-angle lens, in which the artificial landmarks are installed at a ceiling of a working zone and the camera built in the mobile robot measures the position of the mobile robot using the landmarks photographed by the camera.
2. Description of the Related Art
A method of implementing an autonomous robot navigation generally includes a localization method that can directly catch the position information of a mobile robot in a moving environment of the mobile robot, a guidance method that generates a moving path in the moving environment from the localization method and controls a robot platform along a corresponding path, and an environment map building method that collects and manages the information on the moving environment of the robot.
The environment map building method can be classified into a metric path generation method which builds a metric map and a topological path generation method which builds a topology map. The metric path generation method indicates methods of selecting a robot path by optimizing a preset performance index with respect to a robot path generated from a robot environment data quantitatively expressed. A representative of the metric path generation method is a case that an environment map in the form of an indoor plane view having a grid structure and an optimal control method considering an optimal path within this environment map or a kinematic structure of a robot platform are selected.
On the other hand, the topological path generation method can build an environment map in the form of a graph expressing characteristic positions within a robot environment, for example, a spatial relationship between respective characteristic points from references such as a furniture, an electronic appliance, or a door entrance and also build a path, for example, “passes the door and moves to a side of a refrigerator” from the built environment map.
As aforementioned, to allow the mobile robot to move along a given path or to built a new path, it is essentially required to collect information on the current position of the mobile robot and to allow the mobile robot to confirm a self-position whenever necessary. For this purpose, artificial landmarks may be installed within the moving environment of the mobile robot or natural landmarks may be extracted from a given environment. Also, an active landmark, such as light or an RF signal may be projected to measure a direction of arrival of a corresponding signal, thereby catching the position of the mobile robot.
Therefore, in recent years, position recognition techniques are being researched, which enable the mobile robot to presume the self-position from the given environment map information and characteristic information of surroundings even through the mobile robot does not conceive the self-position.
An example which uses the artificial landmarks to trace the self-position of the mobile robot is disclosed in Korean Patent Publication No. 2003-0026496 entitled “Artificial Landmark Apparatus for Landmark based Self-Localization of Mobile Robot”. This cited reference is to overcome a drawback that when the artificial landmark is recognized using an image processing method, a recognition result is influenced by an environmental luminance, and enables the mobile robot to recognize the landmarks and autonomically navigate even in a low luminance environment or a dark environment by installing an illumination apparatus for a constant luminance around the artificial landmarks.
However, the aforementioned prior art has an inconvenience that a separate illumination apparatus and an illumination control apparatus for controlling the separate illumination apparatus should be installed. Also, the prior art fails to presume a global localization and an azimuth angle within an entire environment of the mobile robot and has a difficulty in presuming the self-position and the azimuth angle according to a change of the illumination.